When fires spread through neighborhoods, they burn all kinds of materials found in cars and houses and everything around them – electronics, paint, plastic, furniture.

Research shows that mixing the chemicals released when man-made materials like this burn are different from what is released during vegetation fires and can be more toxic. Smoke and ash can blow under the doors and around the windows of neighboring houses, carrying chemicals that are absorbed by furniture, walls, and other indoor surfaces and keep the gas free inside. weeks to months.

As people return to smoke-damaged homes after the fire, there are many steps they can take to protect their health before starting to clean.

High levels of metals and VOCs

In 2021, after the Marshall Fire tore through neighborhoods near Boulder, Colorado, my colleagues and I at Colorado universities and laboratories heard from many residents concerned about ash and lingering smell inside their homes who otherwise escaped the flames.

In the houses that my colleagues quickly tested, they found high levels of metals and PAHs – polycyclic aromatic hydrocarbons – in the ash. We also found high levels of VOCs – volatile organic compounds – in the air samples. Some VOCs, such as dioxins, benzene, formaldehyde and PAHscan be toxic to humans. Benzene is a known carcinogens.

At that time, we were unable to find information about the physical health of people who returned to smoke-damaged homes after the fire. So, in search of patterns, we surveyed residents affected by the fire six months, one year and two years after the fire.

Even six months after the fire, we found that many people have reported symptoms which is consistent with the health risks associated with smoke and ash from fires.

More than half (55%) reported experiencing at least one symptom six months after the fire that they attributed to the Marshall Fire. The most common symptoms reported were itchy or watery eyes (33%), headache (30%), dry cough (27%), sneezing (26%) and sore throat (23%).

All of these symptoms, as well as having a strange taste in the mouth, have been associated with people reporting that their home smelled different when they returned to it a week after the fire.

Many respondents to the survey said that the odors have decreased over time. Many attribute the development of the odor to the passage of time, cleaning surfaces and air ducts, changing furnace filters, and removing carpet, textiles and furniture from the home. Despite this, many still have symptoms.

We also found that living near many burned structures was associated with these health symptoms. We found that for every 10 additional damaged buildings within 820 feet (250 meters) of a person’s home, there was an associated 21% increase in headaches and a 26% increase in having a strange -an taste in their mouth.

These symptoms are consistent with what would be expected from exposure to the chemicals we found in the ash and measured in some indoor air. smoke damaged houses we studied in depth.

Lingering symptoms and questions

There are still many unanswered questions about health risks from smoke and ash damaged homes.

For example, we don’t yet know what the long-term health implications look like for people living with lingering gases from fire smoke and ash in a home. We found an important one decrease in the number of people reporting symptoms one year after the fire. However, 33% percent of people whose homes were affected and responded to a later survey still reported at least one symptom they attributed to the fire. About the same percentage also reported at least one symptom two years after the fire.

We also cannot measure the level of VOCs or metals that each person is exposed to. But we believe that reports of a change in the smell of someone’s home a week after the fire indicate the possibility of VOCs in the home. That could have health implications for people whose homes are exposed to smoke or ash from a wildfire.

Tips to protect yourself after wildfires

Wildfires are more and more burning houses and other structures As more people move the wildland-urban interface, rise in temperature and fire seasons lengthen.

If your home has survived a wildfire nearby, here are some of the steps to consider before starting to clean:

• If you’re ready to clean your home, start by protecting yourself. Wear an N95 (or KN95) mask and gloves, goggles and clothing that covers your skin. Cleaning can send some of the gases and ash back into the air.
• Keep people with heart or lung disease, the elderly, pregnant women, children and pets away from cleaning activities.
• Vacuum floors, curtains and furniture. A recent scientific study documents how cleaning all surfaces inside a home can reduce reservoirs of VOCs and lower indoor air concentrations of VOCs. If the air outside is empty, open the windows to let in fresh air.
• Avoid harsh cleaning chemicals as they can react with the chemicals in the ash.
• Clean your HVAC filter and ducts to prevent the spread of ash, and change the filters monthly until the odor is gone. Portable air cleaners with carbon filters help remove VOCs and particulates.
• If your car smells like smoke, consider replacing the cabin air filter.

This is an update to an article first published on December 23, 2024.

Colleen E. ReidAssociate Professor of Geography, University of Colorado Boulder

This article was reprinted from The Conversation under Creative Commons license. Read the original article.